[RFC PATCH 00/10] mm/damon: extend DAMOS filters for inclusion of target memory

[RFC PATCH 00/10] mm/damon: extend DAMOS filters for inclusion of target memory

[SeongJae Park]

DAMOS fitlers are exclusive filters.  It only excludes memory of
specific types from the DAMOS action targets.  This has below problems.

First, the name is not explicitly explaining the behavior.  This
actually resulted in confusions[1] and works to improve the siaution[2],
including wordsmithing documentations and adding features to DAMON
user-space tool, damo.

Secondly, the functionality is restrictive.  This is especially
problematic when multiple filters need to be used.  For example,
building a DAMOS scheme that applies the action to memory that belongs
to cgroup A "or" cgroup B is impossible.  A workaroudn is using two
schemes, each filtering out memory that not belong to cgroup A and
cgroup B, respectively.  It is cumbersome, and makes control of
quota-like additional factors difficult.

Extend DAMOS filters to support not only excluding (blocking), but also
including (pass-through) behavior.  For the extension, add a new
damos_filter struct field called 'pass' for DAMON kernel API users.
Using the API, add a DAMON sysfs file of same name under DAMOS filter
sysfs directory, for DAMON user-space ABI users.  To prevent breaking
old users with a behavioral change, set the blocking as the default
behavior.

Note that DAMOS' default behavior without DAMOS filters is applying the
action to any memory.  And DAMOS filters work for only memory that
satisfies 'type' and 'matching'.  Hence installing pass filter without
any block filter after them makes no filter-behavioral change.

[1] https://lore.kernel.org/20240320165619.71478-1-sj@kernel.org
[2] https://git.kernel.org/sj/damo/c/b6a722c85ff91e5abe9dd47135e300df243da056

SeongJae Park (10):
  mm/damon: fixup damos_filter kernel-doc
  mm/damon/core: add damos_filter->pass field
  mm/damon/core: support damos_filter->pass
  mm/damon/paddr: support damos_filter->pass
  mm/damon: add pass argument to damos_new_filter()
  mm/damon/sysfs-schemes: add a file for setting damos_filter->pass
  Docs/mm/damon/design: document pass/block filters behaviors
  Docs/ABI/damon: document DAMOS filter pass sysfs file
  Docs/admin-guide/mm/damon/usage: omit DAMOS filter details in favor of
    design doc
  Docs/admin-guide/mm/damon/usage: document DAMOS filter 'pass' sysfs
    file

 .../ABI/testing/sysfs-kernel-mm-damon         | 14 +++--
 Documentation/admin-guide/mm/damon/usage.rst  | 55 ++++++++++---------
 Documentation/mm/damon/design.rst             | 29 ++++++++--
 include/linux/damon.h                         | 15 +++--
 mm/damon/core.c                               | 12 ++--
 mm/damon/paddr.c                              |  9 +--
 mm/damon/reclaim.c                            |  2 +-
 mm/damon/sysfs-schemes.c                      | 32 ++++++++++-
 mm/damon/tests/core-kunit.h                   | 14 ++---
 9 files changed, 125 insertions(+), 57 deletions(-)

-- 
2.39.5

[RFC PATCH 01/10] mm/damon: fixup damos_filter kernel-doc

[SeongJae Park]

The comment is slightly wrong.  DAMOS filters are not only for pages,
but general bytes of memory.  Also the description of 'matching' is bit
confusing, since DAMOS filters do only filtering out.  Update the
comments to be less confusing.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 include/linux/damon.h | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 18449b5c45df..15f098372672 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -347,8 +347,8 @@ enum damos_filter_type {
 
 /**
  * struct damos_filter - DAMOS action target memory filter.
- * @type:	Type of the page.
- * @matching:	If the matching page should filtered out or in.
+ * @type:	Type of the target memory.
+ * @matching:	If the @type-matching memory should be filtered out.
  * @memcg_id:	Memcg id of the question if @type is DAMOS_FILTER_MEMCG.
  * @addr_range:	Address range if @type is DAMOS_FILTER_TYPE_ADDR.
  * @target_idx:	Index of the &struct damon_target of
@@ -357,9 +357,10 @@ enum damos_filter_type {
  * @list:	List head for siblings.
  *
  * Before applying the &damos->action to a memory region, DAMOS checks if each
- * page of the region matches to this and avoid applying the action if so.
- * Support of each filter type depends on the running &struct damon_operations
- * and the type.  Refer to &enum damos_filter_type for more detai.
+ * byte of the region matches to this given condition and avoid applying the
+ * action if so.  Support of each filter type depends on the running &struct
+ * damon_operations and the type.  Refer to &enum damos_filter_type for more
+ * details.
  */
 struct damos_filter {
 	enum damos_filter_type type;
-- 
2.39.5

[RFC PATCH 02/10] mm/damon/core: add damos_filter->pass field

[SeongJae Park]

DAMOS filters work as only exclusive (block) filters.  This makes it
easy to be confused, and restrictive at combining multiple filters for
various types of memory.

To extend DAMOS filters for inclusion behavior, add a filed to
damos_filter.  Following commits will make the field to decide whether
the filter should work as an exclusive (block) filter, or an inclusive
(pass) filter.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 include/linux/damon.h | 4 +++-
 mm/damon/core.c       | 1 +
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 15f098372672..122c30e4ce19 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -348,7 +348,8 @@ enum damos_filter_type {
 /**
  * struct damos_filter - DAMOS action target memory filter.
  * @type:	Type of the target memory.
- * @matching:	If the @type-matching memory should be filtered out.
+ * @matching:	Whether this is for @type-matching memory.
+ * @pass:	Whether the memory should pass-through the filter.
  * @memcg_id:	Memcg id of the question if @type is DAMOS_FILTER_MEMCG.
  * @addr_range:	Address range if @type is DAMOS_FILTER_TYPE_ADDR.
  * @target_idx:	Index of the &struct damon_target of
@@ -365,6 +366,7 @@ enum damos_filter_type {
 struct damos_filter {
 	enum damos_filter_type type;
 	bool matching;
+	bool pass;
 	union {
 		unsigned short memcg_id;
 		struct damon_addr_range addr_range;
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 52e50f183ffe..e54bd19d6f06 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -275,6 +275,7 @@ struct damos_filter *damos_new_filter(enum damos_filter_type type,
 		return NULL;
 	filter->type = type;
 	filter->matching = matching;
+	filter->pass = false;
 	INIT_LIST_HEAD(&filter->list);
 	return filter;
 }
-- 
2.39.5

[RFC PATCH 03/10] mm/damon/core: support damos_filter->pass

[SeongJae Park]

DAMON core logic is ignoring damos_filter->pass by assuming the value
will be false.  Respect it by dropping the assumption and reading the
field when making the decision to whether filter out or in a region.

Note that DAMOS action can be applied to any memory if no filter is
installed, and DAMOS filters work only for memory that satisfies the
'type' and 'matching'.  Hence installing pass filters without any block
filter after them makes no filter-behavioral change.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/core.c             |  6 +++---
 mm/damon/tests/core-kunit.h | 10 +++++-----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/mm/damon/core.c b/mm/damon/core.c
index e54bd19d6f06..71db2c754e6d 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -1374,7 +1374,7 @@ static void damos_update_stat(struct damos *s,
 	s->stat.sz_ops_filter_passed += sz_ops_filter_passed;
 }
 
-static bool __damos_filter_out(struct damon_ctx *ctx, struct damon_target *t,
+static bool damos_filter_match(struct damon_ctx *ctx, struct damon_target *t,
 		struct damon_region *r, struct damos_filter *filter)
 {
 	bool matched = false;
@@ -1428,8 +1428,8 @@ static bool damos_filter_out(struct damon_ctx *ctx, struct damon_target *t,
 	struct damos_filter *filter;
 
 	damos_for_each_filter(filter, s) {
-		if (__damos_filter_out(ctx, t, r, filter))
-			return true;
+		if (damos_filter_match(ctx, t, r, filter))
+			return !filter->pass;
 	}
 	return false;
 }
diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index cf22e09a3507..8f58d3424c21 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -434,25 +434,25 @@ static void damos_test_filter_out(struct kunit *test)
 	damon_add_region(r, t);
 
 	/* region in the range */
-	KUNIT_EXPECT_TRUE(test, __damos_filter_out(NULL, t, r, f));
+	KUNIT_EXPECT_TRUE(test, damos_filter_match(NULL, t, r, f));
 	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1);
 
 	/* region before the range */
 	r->ar.start = DAMON_MIN_REGION * 1;
 	r->ar.end = DAMON_MIN_REGION * 2;
-	KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f));
+	KUNIT_EXPECT_FALSE(test, damos_filter_match(NULL, t, r, f));
 	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1);
 
 	/* region after the range */
 	r->ar.start = DAMON_MIN_REGION * 6;
 	r->ar.end = DAMON_MIN_REGION * 8;
-	KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f));
+	KUNIT_EXPECT_FALSE(test, damos_filter_match(NULL, t, r, f));
 	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1);
 
 	/* region started before the range */
 	r->ar.start = DAMON_MIN_REGION * 1;
 	r->ar.end = DAMON_MIN_REGION * 4;
-	KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f));
+	KUNIT_EXPECT_FALSE(test, damos_filter_match(NULL, t, r, f));
 	/* filter should have split the region */
 	KUNIT_EXPECT_EQ(test, r->ar.start, DAMON_MIN_REGION * 1);
 	KUNIT_EXPECT_EQ(test, r->ar.end, DAMON_MIN_REGION * 2);
@@ -465,7 +465,7 @@ static void damos_test_filter_out(struct kunit *test)
 	/* region started in the range */
 	r->ar.start = DAMON_MIN_REGION * 2;
 	r->ar.end = DAMON_MIN_REGION * 8;
-	KUNIT_EXPECT_TRUE(test, __damos_filter_out(NULL, t, r, f));
+	KUNIT_EXPECT_TRUE(test, damos_filter_match(NULL, t, r, f));
 	/* filter should have split the region */
 	KUNIT_EXPECT_EQ(test, r->ar.start, DAMON_MIN_REGION * 2);
 	KUNIT_EXPECT_EQ(test, r->ar.end, DAMON_MIN_REGION * 6);
-- 
2.39.5

[RFC PATCH 04/10] mm/damon/paddr: support damos_filter->pass

[SeongJae Park]

'paddr', a DAMON operations set implementation for the physical address
space supports a few types of DAMOS filters (anon, memcg and young), but
ignoring the ->pass field.  Update the logic to support the behavior.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/paddr.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index b0c283808ba6..71cb02128b46 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -198,7 +198,7 @@ static unsigned int damon_pa_check_accesses(struct damon_ctx *ctx)
 	return max_nr_accesses;
 }
 
-static bool __damos_pa_filter_out(struct damos_filter *filter,
+static bool damos_pa_filter_match(struct damos_filter *filter,
 		struct folio *folio)
 {
 	bool matched = false;
@@ -237,8 +237,8 @@ static bool damos_pa_filter_out(struct damos *scheme, struct folio *folio)
 	struct damos_filter *filter;
 
 	damos_for_each_filter(filter, scheme) {
-		if (__damos_pa_filter_out(filter, folio))
-			return true;
+		if (damos_pa_filter_match(filter, folio))
+			return !filter->pass;
 	}
 	return false;
 }
-- 
2.39.5

[RFC PATCH 05/10] mm/damon: add pass argument to damos_new_filter()

[SeongJae Park]

damos_new_filter() sets damos_filter->pass as false always.  The API
users hence should manually set the field to use the filter as a pass
filter.  It is cumbersome and easy to mistake.  Add an arugment for
setting the field to damos_new_filter().

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 include/linux/damon.h       | 2 +-
 mm/damon/core.c             | 7 ++++---
 mm/damon/paddr.c            | 3 ++-
 mm/damon/reclaim.c          | 2 +-
 mm/damon/sysfs-schemes.c    | 2 +-
 mm/damon/tests/core-kunit.h | 4 ++--
 6 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 122c30e4ce19..ad0360711aca 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -801,7 +801,7 @@ void damon_update_region_access_rate(struct damon_region *r, bool accessed,
 		struct damon_attrs *attrs);
 
 struct damos_filter *damos_new_filter(enum damos_filter_type type,
-		bool matching);
+		bool matching, bool pass);
 void damos_add_filter(struct damos *s, struct damos_filter *f);
 void damos_destroy_filter(struct damos_filter *f);
 
diff --git a/mm/damon/core.c b/mm/damon/core.c
index 71db2c754e6d..13f12d82de5f 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -266,7 +266,7 @@ int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges,
 }
 
 struct damos_filter *damos_new_filter(enum damos_filter_type type,
-		bool matching)
+		bool matching, bool pass)
 {
 	struct damos_filter *filter;
 
@@ -275,7 +275,7 @@ struct damos_filter *damos_new_filter(enum damos_filter_type type,
 		return NULL;
 	filter->type = type;
 	filter->matching = matching;
-	filter->pass = false;
+	filter->pass = pass;
 	INIT_LIST_HEAD(&filter->list);
 	return filter;
 }
@@ -806,7 +806,8 @@ static int damos_commit_filters(struct damos *dst, struct damos *src)
 			continue;
 
 		new_filter = damos_new_filter(
-				src_filter->type, src_filter->matching);
+				src_filter->type, src_filter->matching,
+				src_filter->pass);
 		if (!new_filter)
 			return -ENOMEM;
 		damos_commit_filter_arg(new_filter, src_filter);
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 71cb02128b46..cd89500efc22 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -259,7 +259,8 @@ static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s,
 		}
 	}
 	if (install_young_filter) {
-		filter = damos_new_filter(DAMOS_FILTER_TYPE_YOUNG, true);
+		filter = damos_new_filter(
+				DAMOS_FILTER_TYPE_YOUNG, true, false);
 		if (!filter)
 			return 0;
 		damos_add_filter(s, filter);
diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
index 9e0077a9404e..a675150965e0 100644
--- a/mm/damon/reclaim.c
+++ b/mm/damon/reclaim.c
@@ -221,7 +221,7 @@ static int damon_reclaim_apply_parameters(void)
 	}
 
 	if (skip_anon) {
-		filter = damos_new_filter(DAMOS_FILTER_TYPE_ANON, true);
+		filter = damos_new_filter(DAMOS_FILTER_TYPE_ANON, true, false);
 		if (!filter)
 			goto out;
 		damos_add_filter(scheme, filter);
diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index deeaf23c1fcf..9a883e8aea1c 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1901,7 +1901,7 @@ static int damon_sysfs_add_scheme_filters(struct damos *scheme,
 			sysfs_filters->filters_arr[i];
 		struct damos_filter *filter =
 			damos_new_filter(sysfs_filter->type,
-					sysfs_filter->matching);
+					sysfs_filter->matching, false);
 		int err;
 
 		if (!filter)
diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h
index 8f58d3424c21..532c6a6f21f9 100644
--- a/mm/damon/tests/core-kunit.h
+++ b/mm/damon/tests/core-kunit.h
@@ -411,7 +411,7 @@ static void damos_test_new_filter(struct kunit *test)
 {
 	struct damos_filter *filter;
 
-	filter = damos_new_filter(DAMOS_FILTER_TYPE_ANON, true);
+	filter = damos_new_filter(DAMOS_FILTER_TYPE_ANON, true, false);
 	KUNIT_EXPECT_EQ(test, filter->type, DAMOS_FILTER_TYPE_ANON);
 	KUNIT_EXPECT_EQ(test, filter->matching, true);
 	KUNIT_EXPECT_PTR_EQ(test, filter->list.prev, &filter->list);
@@ -425,7 +425,7 @@ static void damos_test_filter_out(struct kunit *test)
 	struct damon_region *r, *r2;
 	struct damos_filter *f;
 
-	f = damos_new_filter(DAMOS_FILTER_TYPE_ADDR, true);
+	f = damos_new_filter(DAMOS_FILTER_TYPE_ADDR, true, false);
 	f->addr_range = (struct damon_addr_range){
 		.start = DAMON_MIN_REGION * 2, .end = DAMON_MIN_REGION * 6};
 
-- 
2.39.5

[RFC PATCH 06/10] mm/damon/sysfs-schemes: add a file for setting damos_filter->pass

[SeongJae Park]

Only kernel-space DAMON API users can use inclusive DAMOS filters.  Add
a sysfs file named 'pass' under DAMOS filter directory of DAMON sysfs
interface, to let the user-space users use inclusive DAMOS filters.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs-schemes.c | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 9a883e8aea1c..9e171046ee94 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -313,6 +313,7 @@ struct damon_sysfs_scheme_filter {
 	struct kobject kobj;
 	enum damos_filter_type type;
 	bool matching;
+	bool pass;
 	char *memcg_path;
 	struct damon_addr_range addr_range;
 	int target_idx;
@@ -385,6 +386,30 @@ static ssize_t matching_store(struct kobject *kobj,
 	return count;
 }
 
+static ssize_t pass_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
+			struct damon_sysfs_scheme_filter, kobj);
+
+	return sysfs_emit(buf, "%c\n", filter->pass ? 'Y' : 'N');
+}
+
+static ssize_t pass_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
+			struct damon_sysfs_scheme_filter, kobj);
+	bool pass;
+	int err = kstrtobool(buf, &pass);
+
+	if (err)
+		return err;
+
+	filter->pass = pass;
+	return count;
+}
+
 static ssize_t memcg_path_show(struct kobject *kobj,
 		struct kobj_attribute *attr, char *buf)
 {
@@ -482,6 +507,9 @@ static struct kobj_attribute damon_sysfs_scheme_filter_type_attr =
 static struct kobj_attribute damon_sysfs_scheme_filter_matching_attr =
 		__ATTR_RW_MODE(matching, 0600);
 
+static struct kobj_attribute damon_sysfs_scheme_filter_pass_attr =
+		__ATTR_RW_MODE(pass, 0600);
+
 static struct kobj_attribute damon_sysfs_scheme_filter_memcg_path_attr =
 		__ATTR_RW_MODE(memcg_path, 0600);
 
@@ -497,6 +525,7 @@ static struct kobj_attribute damon_sysfs_scheme_filter_damon_target_idx_attr =
 static struct attribute *damon_sysfs_scheme_filter_attrs[] = {
 	&damon_sysfs_scheme_filter_type_attr.attr,
 	&damon_sysfs_scheme_filter_matching_attr.attr,
+	&damon_sysfs_scheme_filter_pass_attr.attr,
 	&damon_sysfs_scheme_filter_memcg_path_attr.attr,
 	&damon_sysfs_scheme_filter_addr_start_attr.attr,
 	&damon_sysfs_scheme_filter_addr_end_attr.attr,
@@ -1901,7 +1930,8 @@ static int damon_sysfs_add_scheme_filters(struct damos *scheme,
 			sysfs_filters->filters_arr[i];
 		struct damos_filter *filter =
 			damos_new_filter(sysfs_filter->type,
-					sysfs_filter->matching, false);
+					sysfs_filter->matching,
+					sysfs_filter->pass);
 		int err;
 
 		if (!filter)
-- 
2.39.5

[RFC PATCH 07/10] Docs/mm/damon/design: document pass/block filters behaviors

[SeongJae Park]

Update DAMOS filters design document to describe the pass/block
behavior of filters.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 Documentation/mm/damon/design.rst | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
index 5ebb572d0999..0265aaef2544 100644
--- a/Documentation/mm/damon/design.rst
+++ b/Documentation/mm/damon/design.rst
@@ -504,9 +504,30 @@ have a list of latency-critical processes.
 
 To let users optimize DAMOS schemes with such special knowledge, DAMOS provides
 a feature called DAMOS filters.  The feature allows users to set an arbitrary
-number of filters for each scheme.  Each filter specifies the type of target
-memory, and whether it should exclude the memory of the type (filter-out), or
-all except the memory of the type (filter-in).
+number of filters for each scheme.  Each filter specifies
+
+- a type of memory (``type``),
+- whether it is for the memory of the type or all except the type
+  (``matching``), and
+- whether it is to allow (pass through the filter) or reject (block) applying
+  the scheme's action to the memory (``pass``).
+
+When multiple filters are installed, each filter is applied in the installed
+order.  If a memory is matched to one of the filter, followup filters are
+ignored.  For example, let's assume a filter for passing anonymous pages and
+another filter for blocking young pages are installed in the order.  If a page
+of a region that eligible to apply the scheme's action is an anonymous page,
+the scheme's action will be applied to the page regardless of whether it is
+young, since it matches with the first filter.  On the other hand, if a page of
+the region is a non-anonymous page, the scheme's action will be applied only if
+the page is young, since the second filter is also applied.
+
+Note that DAMOS action is eligible to be applied to any memory that satisfies
+other conditions if no filter is isntalled.  Meanwhile, DAMOS filters work for
+only memory that satisfies ``type`` and ``matching``.  It means installing only
+pass filters is same to installing no filter, because pass filters dont' block
+memory of type that not specified to pass.  For any use case, at least one
+block filter should be installed as the last one.
 
 For efficient handling of filters, some types of filters are handled by the
 core layer, while others are handled by operations set.  In the latter case,
@@ -516,7 +537,7 @@ filter are not counted as the scheme has tried to the region.  In contrast, if
 a memory regions is filtered by an operations set layer-handled filter, it is
 counted as the scheme has tried.  This difference affects the statistics.
 
-Below types of filters are currently supported.
+Below ``type`` of filters are currently supported.
 
 - anonymous page
     - Applied to pages that containing data that not stored in files.
-- 
2.39.5

[RFC PATCH 08/10] Docs/ABI/damon: document DAMOS filter pass sysfs file

[SeongJae Park]

Update DAMON ABI document for added DAMOS filter 'pass' file.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 Documentation/ABI/testing/sysfs-kernel-mm-damon | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-damon b/Documentation/ABI/testing/sysfs-kernel-mm-damon
index 8c0acb31638b..688bd27d8602 100644
--- a/Documentation/ABI/testing/sysfs-kernel-mm-damon
+++ b/Documentation/ABI/testing/sysfs-kernel-mm-damon
@@ -355,10 +355,16 @@ Description:	If 'target' is written to the 'type' file, writing to or
 What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/filters/<F>/matching
 Date:		Dec 2022
 Contact:	SeongJae Park <sj@kernel.org>
-Description:	Writing 'Y' or 'N' to this file sets whether to filter out
-		pages that do or do not match to the 'type' and 'memcg_path',
-		respectively.  Filter out means the action of the scheme will
-		not be applied to.
+Description:	Writing 'Y' or 'N' to this file sets whether the filter is for
+		the memory of the 'type', or all except the 'type'.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/filters/<F>/pass
+Date:		Dec 2024
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing 'Y' or 'N' to this file sets whether to allow (pass
+		through the filter) or deny (be blocked by the filter) applying
+		the scheme's action to the memory that satisfies the 'type' and
+		the 'matching' of the directory.
 
 What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/stats/nr_tried
 Date:		Mar 2022
-- 
2.39.5

[RFC PATCH 09/10] Docs/admin-guide/mm/damon/usage: omit DAMOS filter details in favor of design doc

[SeongJae Park]

DAMON usage document is describing some details about DAMOS filters,
which are also documented on the design doc.  Deduplicate the details in
favor of the design doc.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 Documentation/admin-guide/mm/damon/usage.rst | 29 ++++++++++----------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst
index a891e830c2a1..fa8a5e4199b1 100644
--- a/Documentation/admin-guide/mm/damon/usage.rst
+++ b/Documentation/admin-guide/mm/damon/usage.rst
@@ -417,13 +417,17 @@ Each filter directory contains six files, namely ``type``, ``matcing``,
 file, you can write one of five special keywords: ``anon`` for anonymous pages,
 ``memcg`` for specific memory cgroup, ``young`` for young pages, ``addr`` for
 specific address range (an open-ended interval), or ``target`` for specific
-DAMON monitoring target filtering.  In case of the memory cgroup filtering, you
-can specify the memory cgroup of the interest by writing the path of the memory
-cgroup from the cgroups mount point to ``memcg_path`` file.  In case of the
-address range filtering, you can specify the start and end address of the range
-to ``addr_start`` and ``addr_end`` files, respectively.  For the DAMON
-monitoring target filtering, you can specify the index of the target between
-the list of the DAMON context's monitoring targets list to ``target_idx`` file.
+DAMON monitoring target filtering.  Meaning of the types are same to the
+description on the :ref:`design doc <damon_design_damos_filters>`.
+
+In case of the memory cgroup filtering, you can specify the memory cgroup of
+the interest by writing the path of the memory cgroup from the cgroups mount
+point to ``memcg_path`` file.  In case of the address range filtering, you can
+specify the start and end address of the range to ``addr_start`` and
+``addr_end`` files, respectively.  For the DAMON monitoring target filtering,
+you can specify the index of the target between the list of the DAMON context's
+monitoring targets list to ``target_idx`` file.
+
 You can write ``Y`` or ``N`` to ``matching`` file to filter out pages that does
 or does not match to the type, respectively.  Then, the scheme's action will
 not be applied to the pages that specified to be filtered out.
@@ -440,14 +444,9 @@ pages of all memory cgroups except ``/having_care_already``.::
     echo /having_care_already > 1/memcg_path
     echo Y > 1/matching
 
-Note that ``anon`` and ``memcg`` filters are currently supported only when
-``paddr`` :ref:`implementation <sysfs_context>` is being used.
-
-Also, memory regions that are filtered out by ``addr`` or ``target`` filters
-are not counted as the scheme has tried to those, while regions that filtered
-out by other type filters are counted as the scheme has tried to.  The
-difference is applied to :ref:`stats <damos_stats>` and
-:ref:`tried regions <sysfs_schemes_tried_regions>`.
+Refer to the :ref:`DAMOS filters design documentation
+<damon_design_damos_filters>` for more details including when each of the
+filters are supported and differences on stats.
 
 .. _sysfs_schemes_stats:
 
-- 
2.39.5

[RFC PATCH 10/10] Docs/admin-guide/mm/damon/usage: document DAMOS filter 'pass' sysfs file

[SeongJae Park]

Update DAMON usage document for the newly added 'pass' sysfs file for
DAMOS filters.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 Documentation/admin-guide/mm/damon/usage.rst | 34 ++++++++++++--------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst
index fa8a5e4199b1..ab343d6ac771 100644
--- a/Documentation/admin-guide/mm/damon/usage.rst
+++ b/Documentation/admin-guide/mm/damon/usage.rst
@@ -89,7 +89,7 @@ comma (",").
     \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd 0/target_metric,target_value,current_value
     \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd :ref:`watermarks <sysfs_watermarks>`/metric,interval_us,high,mid,low
     \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd :ref:`filters <sysfs_filters>`/nr_filters
-    \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd 0/type,matching,memcg_id
+    \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd 0/type,matching,memcg_id,pass
     \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd :ref:`stats <sysfs_schemes_stats>`/nr_tried,sz_tried,nr_applied,sz_applied,sz_ops_filter_passed,qt_exceeds
     \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd :ref:`tried_regions <sysfs_schemes_tried_regions>`/total_bytes
     \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd 0/start,end,nr_accesses,age,sz_filter_passed
@@ -412,13 +412,14 @@ number (``N``) to the file creates the number of child directories named ``0``
 to ``N-1``.  Each directory represents each filter.  The filters are evaluated
 in the numeric order.
 
-Each filter directory contains six files, namely ``type``, ``matcing``,
-``memcg_path``, ``addr_start``, ``addr_end``, and ``target_idx``.  To ``type``
-file, you can write one of five special keywords: ``anon`` for anonymous pages,
-``memcg`` for specific memory cgroup, ``young`` for young pages, ``addr`` for
-specific address range (an open-ended interval), or ``target`` for specific
-DAMON monitoring target filtering.  Meaning of the types are same to the
-description on the :ref:`design doc <damon_design_damos_filters>`.
+Each filter directory contains seven files, namely ``type``, ``matcing``,
+``pass``, ``memcg_path``, ``addr_start``, ``addr_end``, and ``target_idx``.  To
+``type`` file, you can write one of five special keywords: ``anon`` for
+anonymous pages, ``memcg`` for specific memory cgroup, ``young`` for young
+pages, ``addr`` for specific address range (an open-ended interval), or
+``target`` for specific DAMON monitoring target filtering.  Meaning of the
+types are same to the description on the :ref:`design doc
+<damon_design_damos_filters>`.
 
 In case of the memory cgroup filtering, you can specify the memory cgroup of
 the interest by writing the path of the memory cgroup from the cgroups mount
@@ -428,25 +429,30 @@ specify the start and end address of the range to ``addr_start`` and
 you can specify the index of the target between the list of the DAMON context's
 monitoring targets list to ``target_idx`` file.
 
-You can write ``Y`` or ``N`` to ``matching`` file to filter out pages that does
-or does not match to the type, respectively.  Then, the scheme's action will
-not be applied to the pages that specified to be filtered out.
+You can write ``Y`` or ``N`` to ``matching`` file to specify whether the filter
+is for memory that matches the ``type``.  You can write ``Y`` or ``N`` to
+``pass`` file to specify should this filter let the memory that satisfies the
+``type`` and ``matching`` pass though (allow) or be blocked by (reject) the
+filter.  Allowing means the scheme's action will be applied to the memory.
 
 For example, below restricts a DAMOS action to be applied to only non-anonymous
 pages of all memory cgroups except ``/having_care_already``.::
 
     # echo 2 > nr_filters
-    # # filter out anonymous pages
+    # # block anonymous pages
     echo anon > 0/type
     echo Y > 0/matching
+    echo N > 0/pass
     # # further filter out all cgroups except one at '/having_care_already'
     echo memcg > 1/type
     echo /having_care_already > 1/memcg_path
     echo Y > 1/matching
+    echo N > 1/pass
 
 Refer to the :ref:`DAMOS filters design documentation
-<damon_design_damos_filters>` for more details including when each of the
-filters are supported and differences on stats.
+<damon_design_damos_filters>` for more details including how multiple filters
+of different ``pass`` works, when each of the filters are supported, and
+differences on stats.
 
 .. _sysfs_schemes_stats:
 
-- 
2.39.5

Re: [RFC PATCH 10/10] Docs/admin-guide/mm/damon/usage: document DAMOS filter 'pass' sysfs file

[SeongJae Park]

On Thu, 26 Dec 2024 14:14:45 -0800 SeongJae Park <sj@kernel.org> wrote:

> Update DAMON usage document for the newly added 'pass' sysfs file for
> DAMOS filters.
> 
> Signed-off-by: SeongJae Park <sj@kernel.org>
> ---
>  Documentation/admin-guide/mm/damon/usage.rst | 34 ++++++++++++--------
>  1 file changed, 20 insertions(+), 14 deletions(-)
> 
> diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst
> index fa8a5e4199b1..ab343d6ac771 100644
> --- a/Documentation/admin-guide/mm/damon/usage.rst
> +++ b/Documentation/admin-guide/mm/damon/usage.rst
> @@ -89,7 +89,7 @@ comma (",").
>      \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd 0/target_metric,target_value,current_value
>      \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd :ref:`watermarks <sysfs_watermarks>`/metric,interval_us,high,mid,low
>      \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd :ref:`filters <sysfs_filters>`/nr_filters
> -    \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd 0/type,matching,memcg_id
> +    \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd 0/type,matching,memcg_id,pass
>      \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd :ref:`stats <sysfs_schemes_stats>`/nr_tried,sz_tried,nr_applied,sz_applied,sz_ops_filter_passed,qt_exceeds
>      \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd :ref:`tried_regions <sysfs_schemes_tried_regions>`/total_bytes
>      \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd \ufffd\ufffd\ufffd 0/start,end,nr_accesses,age,sz_filter_passed

Oops, seems my new patch format script has an encoding handling bug.  I will
fix this on next spin...


Thanks,
SJ

[...]